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# Stuck on a Conic watch

1. (Original post by TeeEm)
correct now
Aw yiss. Is 2a = 5?
2. (Original post by Zacken)
Aw yiss. Is 2a = 5?
it is
3. (Original post by TeeEm)
it is
I made a simple error at the end, I said 2*5/2 = 2.......
4. (Original post by Zacken)
I made a simple error at the end, I said 2*5/2 = 2.......
I will post my solutions (the polar version is interesting )
one of the things maths lacks this days is you cannot get a question such as this as polars and conics are in different modules
5. (Original post by TeeEm)
I will post my solutions (the polar version is interesting )
one of the things maths lacks this days is you cannot get a question such as this as polars and conics are in different modules
You can! Like, for example - there are no pulleys in M2, but this year, my paper had pulleys because it was still in M1! Tag me when you put the polar version up, I'd be interested in having a look at it!
6. (Original post by Zacken)
You can! Like, for example - there are no pulleys in M2, but this year, my paper had pulleys because it was still in M1! Tag me when you put the polar version up, I'd be interested in having a look at it!
...
Attached Images
7. IMG.pdf (217.4 KB, 59 views)
8. I see I am too late, anyways...

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Attached Images

9. (Original post by DylanJ42)
I see I am too late, anyways...

Posted from TSR Mobile
Friday night you see ... I am going to a party ...
10. Conics are on my list of things to do this half-term break, *bookmarks*
11. (Original post by TeeEm)
Friday night you see ... I am going to a party ...
There is no party like a maths forum party
12. (Original post by TeeEm)
could you point me in the right direction?
Attachment 503155
I think I might be missing a joke here but the property you are asking for (i.e. sum of the distances from the foci is constant) is true for all ellipses, not just the particular one given in the question.

(So the easiest way to do the question is to simply quote that theorem :P)
13. (Original post by TeeEm)
...
Sweet, thanks!
14. (Original post by theOldBean)
I think I might be missing a joke here but the property you are asking for (i.e. sum of the distances from the foci is constant) is true for all ellipses, not just the particular one given in the question.
It is, but that doesn't mean you can't prove it for a specific special, can you?
15. (Original post by theOldBean)
I think I might be missing a joke here but the property you are asking for (i.e. sum of the distances from the foci is constant) is true for all ellipses, not just the particular one given in the question.

(So the easiest way to do the question is to simply quote that theorem :P)
Sorry but I make the question and I do not expect the student not to use any well known theorems ...
If I was to put this in an exam i would state it clearly.

All the best !
16. Attachment 503301503303Attachment 503301503303503300
Bit late.
I have no idea why all 3 of these pictures are displayed sideways. I took them from my phone the correct way up.
Attached Images

17. (Original post by theOldBean)
I think I might be missing a joke here but the property you are asking for (i.e. sum of the distances from the foci is constant) is true for all ellipses, not just the particular one given in the question.

(So the easiest way to do the question is to simply quote that theorem :P)
That's what I thought, sum of distance from two foci is = 2 x semi major axis. But I guess in this question you are proving it for a special case.
18. (Original post by TeeEm)
could you point me in the right direction?
I didn't know that ellipses had such elegant polar equations.
19. (Original post by Louisb19)
I didn't know that ellipses had such elegant polar equations.
20. you can draw an ellipse by making a loop of string and putting two nails at the foci. pull the loop tight with a pencil and draw round, keeping it tight.
you can see that the length of string which is moving is constant, as required in this question.

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